The Relationship between Pre- and Postoperative Range of Motion Utilizing Three Cruciate-Retaining Total Knee Prostheses

Abstract

We prospectively examined the relationship between pre- and postoperative range of motion utilizing three cruciate retaining knees with various mechanical flexion potentials, i.e., two at about 130°–135° (one with posterior lip and the other without) and the third at about 140°–145°. All groups demonstrated mean flexion and range of motion of 116°–122° at one year. Combining data from the three cohorts, patients with the following preoperative flexion values achieved the indicated mean changes (increases) in flexion at one year: < 90° flexion (Δ 23.6°), 91°–105°flexion (Δ 19.3°), and > 105° flexion (Δ 1.8°)). Postoperative improvement was inversely related to preoperative flexion. The high flex knee yielded the best improvement in range of motion (9.7°increase) in the highest flex preoperative group compared to that of the other knees (−7.4° to 2.9°). Hence, a high flex knee design seems to be important in high preoperative range of motion patients obtaining an increase in the postoperative range of motion rather than possible regression.